The invention is directed to gusseted large pinch-closure type multi-wall bags requiring side gussets from 5xc2xd-6xe2x80x3 and larger.
Gusseted bags, having top and bottom pinch closeable ends, are typically made in a multi-wall construction having a plurality of paper plies formed as a tube and laterally offset to provide seams for bonding. The top and bottom ends are usually stepped to provide opposing adhesive xe2x80x9cladderedxe2x80x9d bonding surfaces. These bags are generally called freight shipping bags in the industry.
In regard to such bags, there has begun a market demand for large side gussets of 5xc2xd-6xe2x80x3 and greater. It is recognized that bags having single gusset sizes of 5xc2xdxe2x80x3 or less work extremely well for small bags, such as for coffee, popcorn, vacuum cleaners, etc., because they are not highly load-stressed and may be manufactured on standard bag formers and filled on known bag spouting machinery.
The needs for larger gusset pinch closeable bags involve manufacturers who fill and ship the bags with higher bulk density products and that require greater bag volumes and pallet stackability, thus demanding a larger package. Such bulk products include pet foods, granulated food materials, flake-form materials, powdered and granular chemicals, agricultural products, such as potting soil bark, mulch, and the like. Accordingly, bag customers are requiring a wider range of capacity for a range of bulk densities. It is a goal in the industry to replace other bags that are limited in their capability for handling greater weights and volumes.
The industry has also found it beneficial to utilize large gusset bags in order to eliminate overhang when a shipment of bags is palletized.
The freight shipping packing and handling industries have found multi-wall bags with pinch closeable ends widely acceptable because of their relative ease in sealing and compatibility with well known bag closure equipment.
As the industry has sought to increase the size of gussetted pinch closeable bags, two major factors have arisen that compound the problem in producing the larger or wider side gussets required. As would be understood to those skilled in the art, the larger the gusset becomes, the more free board is needed to close the bag at the open end where the filling spout introduces the product. This means that extra paper is needed to close the top of the bag with paper covering the product so the bag has to be made bigger to accommodate this closure. The larger the gusset becomes the deeper the gusset ribs extend into the gusset of the end tuck and more room is required because these large ribs are difficult to push outwardly when the bag is being filled. This can cause irregular bag expansion that might lead to tearing and ripping. Heretofore, the multi-wall bag industry has not successfully developed or accepted large gusseted pinch closeable bags. Alternate ways have been attempted, such as by using other styles of bags. In great measure, larger gussets, i.e. those that would be generally about 6xe2x80x3 or more in width, are difficult to make in single standard fold gussets. Large percentages of the bags manufactured must be discarded as inferior. The bag-making production lines using the larger gussets also have to be run at slower speeds than non-gusseted pinch closeable bag line speeds. As the industry has experienced, urging these large gussets to form in the tuber, due to the bulkiness in size, creates difficulty in handling and machining during the bag making process. The standard guideline in the multi-wall freight shipping bag has been to not specify gussets that are over 5xc2xdxe2x80x3 wide. While certain manufacturers occasionally have provided these larger gussets, there is an inherent weakness at the gussets in large bags.
Antecedent to the present invention, bag manufacturers have not produced multiple gusseted pinch closeable bags. Instead, the industry has chosen to focus its effort in producing small-sized pinch bags having a standard single gusset, such as used for popcorn bags, small coffee bags, microwaveable bags, vacuum cleaner bags, and the like. Accordingly, smaller bags have become the norm with respect to utilizing side or lateral gussets. This is because the large gusseted bags have been found to require more timely machinery set-up for the tuber, former, and flattener, plus the impractical end result that they develop a higher waste at a lower production rate. When large gusset bags have been made in this fashion, the bag manufacturer simply accepts the inherent inefficiency and loss to meet an order of a customer.
Previous attempts at pinch closeable bags having gussets 6xe2x80x3 and over also have had several other problems. For example, when considering a standard 17xe2x80x3 by 33xe2x80x3 by 8xe2x80x3 bag, wherein the 8xe2x80x3 is the gusset and bag width dimension, the gussets are formed in the bag sides lengthwise of the bag creating two gusset walls having a v-shape arrangement. Thus, the gusset is indented 4xe2x80x3 deep on either side of the bag. When the bag lies empty ready to be filled, there are two 4xe2x80x3 tucks at either side wall for a total of 8xe2x80x3, thus leaving 9xe2x80x3 between the inner folds of the v-shapes for a 17xe2x80x3 wide bag. The room for spouting, filling and forming is thus lessened by 8xe2x80x3 compared to a non-gussetted construction. It has been found that single large gussets of this type have difficulty in being outwardly expanded during the filling process because all of the gusset is facing inwardly and the product mass has to push the gusset in the outward direction. The inherent weakness in forcing paper plies outwardly and at localized pressure zones can lead to bag rupture. There is a particular inherent weakness at the inside apex area of the v-shapes at the xe2x80x9cmanufactured endxe2x80x9d (pre-sealed) of the bag. This can result in tearing and upward fracturing of the bag. The large gusset is difficult to fill out and square properly. The resulting gussets of a filled bag are often a little bit less than the intended bag width of 7 or 8xe2x80x3 because the product in the bag does not fully push out the v-shaped gusset. This reduction in bag depth can also affect the presentation of advertising or printing on the bag sides. As would also be clear, because of this inability to shape or xe2x80x9csquare out,xe2x80x9d the filled bag may actually offer a diminished volume capacity inside the bag, which otherwise could be filled with the product.
Therefore, the major goals of the invention are (1) to provide more lateral or inboard room between gussets for forming, filling and spouting; (2) to create easier gusset-shaping during the filling step which allows the gussets to fill outwardly with less localized stress and less product pressure that would otherwise cause rupture in the previously known bags; (3) in providing larger gusseted (deeper) pinch-closeable bags, while maintaining sidewall strength, and (4) allowing the large gussets to be configured in a way so that the filled bags can subsequently be evenly stacked on a pallet without pallet overhang.
The present invention provides a multiple gusset for large freight shipping bags of the pinch closeable style wherein the manufactured end is pinch closed and the opposite open end is later sealed by the customer after filling the bag. The invention includes a unique step pattern and folded construction that when seal closed, satisfies industry wide drop testing strength, machine-ability, moisture barrier requirements, and seal closeability on standard pinch closure equipment. The invention may be summarized as providing a multiple gusset bag of greater than 5xc2xd-6xe2x80x3 depth utilizing an improved seal-closeable stepping pattern, upper and lower end gusset bonds, and a maximized space between inward folds of the gussets to satisfy fill spouting requirements.
Standard pinch closeable three-ply bags with bag widths from about 14-20xe2x80x3 have stepped multi-paper plies with a step pattern length about of 2xc2xcxe2x80x3 or less. For an equivalently sized bag, the present invention provides for a stepping pattern length of 2xe2x85x9c-2xc2xdxe2x80x3 having steps between adjacent ply edges of from {fraction (1/16)}xe2x80x3 up to about {fraction (5/16)}xe2x80x3, which in a preferred embodiment offers a double gusset in a three-ply paper bag. This creates 18 layers of ply thickness at the folded gusset, which when folded to form the pinch closure can create a thickness of over 30 plies at the pinch closed end. Another popular bag size is made of two plies having double-gussets creating a thickness of 12 plies at the gussets.
The inventive multi-gusset bag secures the ends of the gussets in a bonded or tacked arrangement, which does not separate during spouting, but yet allows the gusset portions for the full length of the bag therebetween to expand outwardly during filling.
On each side of the multi-wall bag, the gussets unfold outwardly taking a rectangular shape forming the squared sides of the bag. The multiple gussets extend from end-to-end, i.e., from the manufactured closed end to the upper open end for receipt of the fill spouting. Both ends of the pinch style bag are folded through the gussets. The invention allows the option of making a flush cut for a top sewn closure or otherwise creating a pinch closure at the open end. Space between gusset infolds is maximized for filling and spouting. As compared to an 8xe2x80x3 gusset in the prior art, wherein only a 9xe2x80x3 gap between in-folds is achieved for a 17xe2x80x3 wide bag, the present invention allows for 13xe2x80x3 between the in-folds of the gussets. Increasing the spout entry space is a significant advantage over present standard single gussets in large freight shipping bags.
In providing multiple gussets, by having additional folds at the pinch closeable upper and lower corners, there is difficulty in feeding and gathering these numerous thicknesses, which as stated can be 18 ply thicknesses in a three-ply bag with a double gusset. This creates a problem in holding the bag in proper alignment while it is being filled and after letting it go from the filler to move through the folder and sealer. It is important to hold the gussets in position for an even sealing. Accordingly, the invention includes the aforementioned gusset bonding or tacking at least at the upper open end of the bag in order to hold the gusset in control and to strengthen the bag after it is filled and stacked on a pallet. Thus, the upper ends of the gussets are held together for evenly placing the bag into the sealer after bag filling. This maintains the bag in proper registry so that as it is going through the pinch closure sealer, not only is the gusset prevented from coming open at the top, it also does not allow the gusset to xe2x80x9cbelly down.xe2x80x9d The upper gusset bonding also provides for a straighter feed into the sealing line and creates a cleaner fold at the pinch closeable fold line. Upper gusset bonding also allows the bag to shape up properly as it is filled and does not let the gussets wander or crimp and become uneven to be sealed in an uneven position.
The gusset tacking is also preferably included at both ends of the bag just beyond the fold line. The tacking thereby offers strength also at the bottom manufactured end as the product is charged into the bag to forcefully impact the bottom of a bag. The gusset bonding increases strength and holds the gusset securely together as they are being shaped and pushed outwardly from the bottom to the top.
The added strength achieved by gusset bonding prevents the ends of the bag from being pushed out at any of the four corners as the bag is going through typical bag flatteners and conventional palletizing systems, and then placed upon a pallet.
The unique stepping pattern at both ends of the bag requires that each ply and its adjacent ply are spaced at a minimum of about {fraction (1/16)}-xe2x85x9th inch measured longitudinally. This full stepping avoids product sifting or channeling through the plies by providing for at least the same overlap as in conventional pinch bottom bags, but using less paper by stepping more. This configuration also eliminates the need for mitered inside corners required to open the bag up for filling, which is used in prior art configurations.
In the disclosed preferred embodiment, the multiple gusset bag has double gussets. However, three or more gussets, i.e., each a v-shaped pair of walls, can be provided. The number is mainly limited to the extent that all the thicknesses of the multi-paper plies must be accommodated in bag tubing, forming and, ultimately, bag folding and sealing machinery.